Tuberous Sclerosis (TS) is a dominant multisystem disorder in which growth malformations and tumors occur in brain, skin, heart, eye, kidney, and other organs. TS is one of the most common (1 in 9,500) dominant disorders and one of the most important inherited tumor syndromes and neurocutaneous syndromes. New findings in linkage mapping and cell biology of TS have made this a rapidly moving field of great current interest. Yet there is no book- length publication which integrates the new findings with previous knowledge. Past meetings and workshops on TS have not resulted in publications. The only book on TS, edited by Dr. Manuel R. Gomez (a co- organizer of the proposed conference), 2nd ed. 1988, was written before the recent findings. This is an appropriate time to synthesize new knowledge about TS by holding an international symposium and publishing the papers as a volume of the Annals of the NY Academy of Sciences. The proposed conference (scheduled for April 23-25, 1990, in Bethesda, MD) will be comprehensive and current and will bring together workers from different departments and disciplines for exchange of knowledge and ideas. The program has three general topics, each the focus of one conference day. Day 1 focusses on the clinical phenotypes of TS inv various organ systems with a panel discussion directed toward defining diagnostic criteria for gene carriers. Day 2 focusses on cellular abnormalities in TS (histopathology, immunohistochemistry, immunocytochemistry, and tissue culture data) and their relation to cell adhesion molecules, and neuronal migrations in experimental systems and in normal and abnormal human development. Day 3 focusses on cytogenetics and linkage mapping in TS with a panel discussion on current status and future directions by the workers who have done the linkage studies. Finally, linkage data for neurofibromatosis 1 and 2 and von Hippel-Lindau disease will be presented since these closely related phakomatoses are likely to be related biologically as well.